On Tuesday 30 October 2012 10:59:26 John Thornton did opine: > ER8 collets go down to 0.039" but that only makes it down to #61 > drill... darn it. I do have one of those pin vise things that mount in a > collet and will hold a #80 bit but it is a cheap one. Are you drilling > by hand with the #72 bit? > > John No, no way I can hand hold that precisely John. Even running slow short peck cycles these drills don't last at all well in cold rolled steel. And I may have to do SS, steel seems to be pretty easily stained & corroded by a #209 primer & black substitutes. And actually for that, the smallest would probably be a #68. I put 5 vent holes in a #209 nipple. One in the tip, and 4 around the sides seems to do a decent job. The SS breech plug has about .020" clearance around the stem of the nipple and that gives the "ring of fire" pattern to the ignition when the side vents are directed forward into the powder.
The OEM nipple has 5 #67 vents in the same pattern. But its backside vented & doesn't put enough power into a load of BlackHorn-209 to get it going, its damned hard to light stuff. My version has no backside vents. > On 10/30/2012 9:12 AM, Gene Heskett wrote: > > On Tuesday 30 October 2012 09:50:06 John Thornton did opine: > >> Another reason is collet holders are much shorter than a drill chuck > >> and on Z challenged machines like my BP switching between an end > >> mill holder an a drill chuck is not always a practical thing... but > >> at $200 for a set of collets it will be out of the range of many > >> home shop machinists. I do have a jacobs chuck for my BP but don't > >> use it. > >> > >> John > > > > I have similar problems with my little toy mill. The average, I can > > buy it at Lowes, replacement chuck cannot reliably mount or hold the > > drills I use which can go as small as #72's. If I ever seriously > > damage the chinese Horse brand chuck that came with the mill, I'll be > > out of business for drills under 1/16". And its runout leaves a lot > > to be desired & getting worse. I have to creep up on starting the > > hole and give it time to self- center, if it will, depends on the > > work material. copper plated pcb's are usually ok, TSC's grade of > > steel rod for a BP nipple gets very very pickity & needs wholesale > > qty's of the chosen bit size because that dulls them rapidly. And > > I've not found anyone who will sell me carbide #68's in ten packs w/o > > a 3 digit price yet. :( > > > > For this sort of work, I seriously need an old 1/4" chuck from a 50 yo > > electric hand drill, but it still drills holes & I hate to tear up > > something that actually still works after all this time. :) > > > >> On 10/30/2012 7:31 AM, Erik Christiansen wrote: > >>> On 30.10.12 06:15, John Thornton wrote: > >>>> I don't use a drill chuck on any of my mills, I've been told ER > >>>> collets are much better and that is what I use. > >>> > >>> Can't disagree a lot, for milling, anyway. IIRC, it was in a Tormach > >>> document that I read a note similar to this: > >>> > >>> Drill Chucks: > >>> Using a drill chuck to hold a tool used for side cutting is > >>> dangerous, though educational and often expensive. A Jacobs > >>> taper is _not_ designed for lateral loads, so vibration and > >>> side loads generally shake the drill chuck off its mount. As > >>> the spinning mass dissipates its kinetic energy, the flailing > >>> cutting edges shred any flesh or other vulnerable material in > >>> its path. Drill chucks are only to be used with axial forces, > >>> i.e. drilling. > >>> > >>> It's now one of my MOTD entries, so once in a while my wetware RAM > >>> is refreshed. > >>> > >>> I'd hate to buy a collet for every drill size I might use. > > > > Amen on that! Not to mention that for my #2 morse spindle, collets > > under 1/8" suddenly are made from unobtainium. > > > >>> Erik > >> > >> --------------------------------------------------------------------- > >> --- ------ Everyone hates slow websites. So do we. > >> Make your web apps faster with AppDynamics > >> Download AppDynamics Lite for free today: > >> http://p.sf.net/sfu/appdyn_sfd2d_oct > >> _______________________________________________ > >> Emc-users mailing list > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > Cheers, Gene > > ------------------------------------------------------------------------ > ------ Everyone hates slow websites. So do we. > Make your web apps faster with AppDynamics > Download AppDynamics Lite for free today: > http://p.sf.net/sfu/appdyn_sfd2d_oct > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! The way to fight a woman is with your hat. Grab it and run. ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_sfd2d_oct _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
